When you pay your electricity bill, you are charged not for power but for the energy used. The unit for measuring the energy used is the kilowatthour (kWh).
(a) How many joules are there in one kWh?
(b) How much energy, in kWh, does a 400-W TV set use in a month (30 days), if it is used an average of 6.0 h each day?
(c) If electrical energy costs $0.06 /kWh, what will it cost you to operate the TV set for one month?
the answers are: (a) 3.6 x 106 J (b) 72 kWh (c) $4.32
i need to know how to do this question, please explain each step thankyou so much!!! =D
(a) How many joules are there in one kWh?
(b) How much energy, in kWh, does a 400-W TV set use in a month (30 days), if it is used an average of 6.0 h each day?
(c) If electrical energy costs $0.06 /kWh, what will it cost you to operate the TV set for one month?
the answers are: (a) 3.6 x 106 J (b) 72 kWh (c) $4.32
i need to know how to do this question, please explain each step thankyou so much!!! =D
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1 kilowatt hour = 3 600 000 joules (or 3.6 x 10^6), so really you just multiply
b) 400W times 30 days of 6 hours each = 400*30*6 = 72000 kWH (just multiply kW times hour to get kW hour lol )
* SORRY in case you read this part already, one correction, 72 kWh OR 72000 Wh, sorry not 7200kWh, the extra k is a mistake!
c) well you have the answer to b), just multiply how many kWhours you used (72kWh) times the price per hour ( $0.06)
sorry in hindsight I didn't explain part a properly :
work is defined as energy per unit time, so one Watt = 1 joule per second, therefore 1 kW = 1000 joules per second
now 1 kWh = 1 kW times 1 hour (or 3600 seconds) = 1000 joules per second times 3600 seconds = 3600000 joules
b) 400W times 30 days of 6 hours each = 400*30*6 = 72000 kWH (just multiply kW times hour to get kW hour lol )
* SORRY in case you read this part already, one correction, 72 kWh OR 72000 Wh, sorry not 7200kWh, the extra k is a mistake!
c) well you have the answer to b), just multiply how many kWhours you used (72kWh) times the price per hour ( $0.06)
sorry in hindsight I didn't explain part a properly :
work is defined as energy per unit time, so one Watt = 1 joule per second, therefore 1 kW = 1000 joules per second
now 1 kWh = 1 kW times 1 hour (or 3600 seconds) = 1000 joules per second times 3600 seconds = 3600000 joules